1. Fields of the Invention
The present invention relates to an electric projector screen, especially to a large-size electric projector screen in which a screen fabric is closed and opened by a motor. During the maintenance and replacement of the motor, the screen fabric is located and limited so that damages caused by quickly and vertically opening of the screen fabric due to the gravity are prevented. Moreover, the cleaning, repairing and the replacement of the motor are easier and more convenient. In use, the practical value of the electric projector screen is improved.
2. Descriptions of Related Art
Nowadays, projectors become essential equipment in a lot of large-scale emporiums and conference halls for projecting data and images of various films and video works on a screen fabric of an electric projector screen. The electric projector screen 2 is shown by an explosive view showing structure of an electric projector screen 2 available now in FIG. 7 and an assembled cross sectional view in FIG. 8.
Refer to FIG. 7 and FIG. 8, a fixed seat 21 is mounted with a winding tube 22 therein. A screen fabric 221 is wound around the winding tube 22. A linkage member 23 is fixed and sleeved in the winding tube 22 and a sleeve hole 231 is set at a middle part of the linkage member 23. A locator 24 having an insertion hole 241 on a middle part thereof is fixed at one end of the winding tube 22. A motor 25 is arranged between the linkage member 3 and the locator 24. An output end 251 of the motor 25 is mounted and connected with the sleeve hole 231 of the linkage member 23 while a fixed end 252 of the motor 25 penetrates the insertion hole 241 of the locator 24 so that the motor 25 is fixed on a center of the winding tube 22 by the locator 24. Moreover, a cover is covered on one end of the fixed seat 21. The fixed end 252 of the motor is further connected to and fixed by a fixing hole 261 of the cover 26.
Thereby, the linkage member 23 is rotated and driven by the output end 251 of the motor 25 assembled and connected with. Thus the screen fabric 221 is rolled up/down by the winding tube 22 moved along with the rotation of the linkage member 23. When the motor 25 needs to be cleaned, repaired or replaced, refer to FIG. 9, the cover 26 is disassembled and the motor 25 is removed from the winding tube 22 for maintenance and replacement.
However, the electric projector screen in which the screen fabric is opened/closed by the motor still have some problems in use while the motor is removed for maintenance and replacement. In practice, the output end of the motor is not locked and connected with the linkage member once the motor is removed. Thus the linkage member is not located by the motor that is not rotating and the screen fabric is pulled down quickly due to a certain weight of the screen fabric. This leads to damages of the screen fabric. For motor maintenance and replacement, the projector screen also needs to be disassembled and this causes inconvenience. Thus there is a need to improve the structure of the electric projector screen available now.